In this activity, students compute the strengths of the gravitational forces exerted on the Moon by the Sun and by the Earth, and demonstrate the actual shape of the Moon's orbit around the Sun. The lesson begins with students' assumptions about the...(View More) motions of the Moon about the Earth and the Earth about the Sun, and then test their understanding using an experimental apparatus made from a cardboard or plywood disk and rope. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.(View Less)